nixpkgs/pkgs/build-support/setup-hooks/prune-libtool-files.sh

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pruneLibtoolFiles: init setup hook (#41819) A .la file specifies linker flags to link with the library it describes. Its "dependency_libs" field lists the libraries that this library depends upon. This list often contains "-l" flags without corresponding "-L" flags. Many packages in Nixpkgs deal with this in one of these ways: - delete .la file [1] - clear dependency_libs [2] - add -L flags to dependency_libs [3] - propagate dependencies [4] Sometimes "dependency_libs" contain wrong "-L" flags pointing to the "dev" output with headers rather than to the main output with libraries. They have to be edited or deleted to reduce closure size [5]. Deleting .la files is often but not always safe [6]. Atomatically deleting as many of them as possible is complex [7]. Deleting .la files that describe shared rather than static libraries is probably safe; but clearing their "dependency_libs" field achieves the same effect with less potential for unintended consequences. This is the approach that may be enabled for all Nixpkgs. [1] https://github.com/NixOS/nixpkgs/commit/2a79d296d3de74da77b49ca8dc9d356b1a7a1c8d [2] https://github.com/NixOS/nixpkgs/commit/c83a53098599c49ec57823bf655ce8b45f6aea10 [3] https://github.com/NixOS/nixpkgs/commit/9e0dcf3bd9fcfeed576132b9101b866aa3cb76ff [4] https://github.com/NixOS/nixpkgs/commit/01134e698fdfb3b61f8ab8ec3bf13e0718f63955 [5] https://github.com/NixOS/nixpkgs/commit/f6c73f1e37c735abb686d07449f349b796c54cf8 [6] https://wiki.gentoo.org/wiki/Project:Quality_Assurance/Handling_Libtool_Archives [7] https://github.com/gentoo/gentoo/blob/fb1f2435/eclass/ltprune.eclass
2018-06-11 19:11:02 +01:00
# Clear dependency_libs in libtool files for shared libraries.
# Shared libraries already encode their dependencies with locations. .la
# files do not always encode those locations, and sometimes encode the
# locations in the wrong Nix output. .la files are not needed for shared
# libraries, but without dependency_libs they do not hurt either.
fixupOutputHooks+=(_pruneLibtoolFiles)
_pruneLibtoolFiles() {
if [ "$dontPruneLibtoolFiles" ]; then
return
fi
# Libtool uses "dlname" and "library_names" fields for shared libraries and
# the "old_library" field for static libraries. We are processing only
# those .la files that do not describe static libraries.
find "$prefix" -type f -name '*.la' \
-exec grep -q '^# Generated by libtool' {} \; \
-exec grep -q "^old_library=''" {} \; \
-exec sed -i {} -e "/^dependency_libs='[^']/ c dependency_libs='' #pruned" \;
}